Resistance welding of thermosetting composite/thermoplastic composite joints

An investigation of the resistance welding between carbon fibre (CF)-reinforced polyetherimide (PEI) and CF-reinforced epoxy laminates is presented. A three-dimensional transient finite element model (FEM) featuring heat transfer, consolidation and thermal degradation was used for simulating the process. A hybrid interlayer made of a glass fibre (GF) fabric essentially impregnated with PEI on one side and with epoxy resin on the other side was produced to provide mechanical interlocking between the thermoplastic (TP) and the thermosetting (TS) systems. The ‘optimal’ resistance welding time based on the maximum lap shear strength (LSS) was determined for three power levels and correlated to the time required to achieve bonding predicted by the FEM. Consolidation quality and failure mechanisms were discussed in relation with processing parameters. Experimental and simulated processing windows were constructed and correlated to each other. However, thermal degradation as predicted by the model did not correlate to a reduction in performance of the joint.